A variety of prior art patents showing compound movement door mechanisms include: U.S. Pat. Nos. 3,346,992; 3,751,995; 3,820,282; 3,888,045; 4,447,026; 4,474,348; 4,589,613; 4,833,827; and U.K. 2,014,231; also, German 2,062,135.
In contrast, the advantages of the present door lifting system over other lifting systems are:
The hinge arm can be located further outboard, giving more cabin area for assist space;
The inboard-outboard movement of the hinge arm is reduced, allowing the interior handle to be located closer to the hinge arm and therefore further outboard;
The fore-and-aft motion of the door relative to the cutout is reduced so that scrubbing of the latch rollers and skin gap is minimized;
The counterbalance spring is moved from the door to the hinge so that the door weight is reduced, thus reducing the force required to lift the door;
The overall part count is reduced when the lifting and counterbalancing is combined;
The overall weight is reduced when compared with the lift link and torsion bar counterbalance design;
Assembly of parts can be accomplished;
Simplified door-to-hinge attachment and counterbalance adjustment;
Counterbalance spring is unloaded when door is removed eliminating danger to maintenance personnel.